In a hospital environment, patient monitors are commonly used to monitor a patient. A patient monitor is a computer system with various input sensors for collecting patient information, a database for saving the information, and a display for displaying the information to a health care provider. Patient information typically includes heart rate, blood pressure, electrocardiographic and electroencephalographic information. Patient information may also include patient descriptive information, such as, patient name, age, etc.
The information collected by the patient monitor is typically categorized as being general or periodic. General information includes patient descriptive information and episodic information. Episodic information are various measurements that are sampled on an ad hoc basis. For example, a health care provider may, from time to time, determine a patient's blood pressure and manually enter the blood pressure reading into the monitor. Periodic information includes various measurements of activity that are sampled continuously, such as, heart rate and electrocardiographic activity.
FIG. 1 is a block diagram illustrating a network of patient monitors in a typical hospital environment. The network comprises a central monitor computer system 101 connected to various patient monitors 102. The central monitor 101 is typically located at a nursing station and allows the activity of many patients to be monitored from the nursing station. The central monitor 101 comprises a central database 111, a controller program 112, and communications program 113. To collect patient information from the patient monitors 102, the controller program 112 instructs the communications program 113 to retrieve the patient information from the patient monitors 102. When the communications program 113 receives the information, it passes the information to the controller program 112. The controller program 112 stores the information in the central database 111. In response to a request to review the information, the controller program 112 retrieves data from the central database 111 and displays the data. The patient monitors 102 comprise a communications program 103, a controller program 104, a patient database 105, and a sensor interface program 106. The controller program 104 controls the collecting of patient information through sensor interface program 106 and the storing of the collected information in the patient database 105. When the communications program 103 receives a request to transmit information to the central monitor 101, the communications program 103 sends the request to the controller program 104, which retrieves the requested information from the patient database 105. The controller program 104 then sends the retrieved information to the communications program 103, which transmits the data to the central monitor 101.
FIG. 2 is a block diagram illustrating typical information stored in the patient database 105. Information in the patient database typically includes a current entry number 201, an audit log 202, a time history list 203, general information 204, and periodic information 205. Whenever information in the patient database is added, an entry number is stored with the added information. Current entry number 201 represents the entry number to be stored with the next added information. The entry number uniquely identifies each entry in the database. The audit log 202 is a table that contains a history of changes to the database. The time history list 203 is a table used to track clock changes in a patient monitor. These changes occur, for example, when someone notices that a clock on the patient monitor is off by ten minutes and then sets the clock ahead by ten minutes. An entry is stored in the time history list 203 indicating a change in time. The time history list allows a reconstruction of the sequence of events that have occurred. When reconstructed, a ten-minute apparent gap in the information would be interpreted not as a ten-minute gap, but rather as a continuous recording of patient information. The general information 204 is stored as a linked list of general information blocks 204A, 204B. Each general information block includes a header containing timing information of the data in the block and includes the general information. The periodic information 205 is stored in trend information blocks. Each trend information block comprises a trend structure 205A and trend stream 206A, 206B. Each trend information block holds information from one type of monitored patient activity (e.g., heart rate). Each trend stream 206A, 206B contains an entry for each measurement made by the patient monitor of the monitored activity. The trend structure 205A includes a pointer to the trend stream 206A, time of the last entry into the trend stream 206A, and various other trend-specific information.
In a hospital environment, patients who are connected to patient monitors are often transported throughout the hospital. For example, after surgery a patient is transported from the operating room to a recovery room. Typically, when a patient is transported, the patient is disconnected from the sensors that are connected to the patient monitor, transported to a new location, and then reconnected to the sensors that are connected to a patient monitor at the new location. Problems are, however, associated with transporting a patient in such a way. First, it can be time-consuming to disconnect and reconnect sensors. Second, the patient monitor at the new location typically cannot access the information that was collected by the patient monitor at the old location. This makes it difficult for a health care provider to track the history of a patient, especially when the patient monitors are not connected to a central monitor. To avoid these problems, the patient monitor can be transported with the patient being connected to the sensors. However, the transporting of patient monitors can be cumbersome and impractical because of their size. Also, various types of patient monitors may be needed that range from very expensive to relatively inexpensive. For example, a patient in an operating room may need extensive monitoring by an expensive patient monitor. It is not cost-effective to transport such an expensive operating room patient monitor to a recovery room and then to the patient's room. It would be more cost-effective to use a less sophisticated (and less expensive) patient monitor in the patient's room.